Hard coating film

ABSTRACT

Disclosed herein is a hard coating film of laminate type which comprises more than one layer of a first kind, which has a composition represented by the formula (1a) below and a thickness of 1 to 80 nm, and more than one layer of a second kind, which has a composition represented by the formula (2a) below and a thickness of 1 to 80 nm, the layers being placed alternately one over another. 
       (Cr (1-a) Al a )(C (1-x) N x )  (1a) 
       (Zr (1-k) Hf k )(C (1-y) N y )  (2a) 
     where each subscript denotes the atomic ratio specified below.
         0.2≦a≦0.8   0.7≦x≦1   0≧k≧1   0.5≦y≦1       

     The hard coating film has outstanding high-temperature characteristics.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hard coating film that can beadvantageously formed on cutting tools (such as tip, drill, and endmill) and jigs (such as forging die and punching die).

2. Description of the Related Art

Conventional cutting tools intended for improved wear resistanceconsists of a substrate of high speed steel, cemented carbide, cermet,or the like and a hard coating film of TiN, TiCN, TiAlN, and the likeformed thereon. Of these hard coating films, that of TiAlN is favorablyapplied to cutting tools for high speed cutting or hard materials suchas hardened steel on account of its very high wear resistance. Therecent trend to harder works and higher cutting speed necessitate thedevelopment of a new hard coating film with better wear resistance.

An example of recent developments is modification of TiAlN into TiCrAlN(by partial substitution of Ti with Cr) as disclosed in PatentDocument 1. According to the disclosure, added Cr increases thecompositional ratio of AlN of rock salt structure, thereby contributingto the hardness and oxidation resistance of the coating film. Anotherexample of recent developments is a hard coating film of CrAlN resultingfrom TiAlN by entire replacement of Ti with Cr, as disclosed in PatentDocument 2.

Patent Document 1:

-   -   Japanese Patent Laid-open No. 2003-71610 (Claim, Paragraphs 0022        and 0023)

Patent Document 2:

-   -   Japanese Patent Laid-open No. Hei-9-41127 (Claims)

OBJECT AND SUMMARY OF THE INVENTION

Although the above-mentioned hard coating films of AiAlN, TiCrAlN, andAlCrN exhibit good oxidation resistance at high temperatures, they areliable to decrease in hardness under harsh conditions involvingextremely high temperatures or intense sliding friction (which resultfrom high speed cutting in a dry state or plastic working with a highareal pressure). In some cases, they undergo the change of crystalstructure for transition into the soft phase. Therefore, they have roomfor improvement in high-temperature characteristics.

The present invention was completed in view of the foregoing. It is anobject of the present invention to provide a hard coating film withimproved high-temperature characteristics.

In order to address the above-mentioned problems, the present inventorscarried out a series of researches which led to the finding that theabove-mentioned object is achieved if a nitride (CrAlN) or carbonitride(CrAlCN) of CrAl is properly combined with Zr or Hf. The presentinvention is based on this finding.

The present invention is directed to a hard coating film of laminatetype which comprises more than one layer of a first kind, which has acomposition represented by the formula (1a) below and a thickness of 1to 80 nm, and more than one layer of a second kind, which has acomposition represented by the formula (2a) below and a thickness of 1to 80 nm, the layers being placed alternately one over another.

(Cr_((1-a))Al_(a))(C_((1-x))N_(x))  (1a)

(Zr_((1-k))Hf_(k))(C_((1-y))N_(y))  (2a)

where each subscript denotes the atomic ratio specified below.

0.2≦a≦0.8

0.7≦x≦1

0≦k≦1

0.5≦y≦1

In one embodiment, the layers of a first kind are replaced at leastpartly by layers having a composition represented by the formula (1b)below and a thickness of 1 to 80 nm, or the layers of a second kind arereplaced at least partly by layers having a composition represented bythe formula (2b) below and a thickness of 1 to 80 nm.

(Cr_((1-a-b-c))Al_(a)Si_(b)B_(c))(C_((1-x))N_(x))  (1b)

where each subscript denotes the atomic ratio specified below, witheither of b and c possibly being 0.

0.2≦a≦0.8

0<(b+c)≦0.2

0.7≦x≦1

(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))(C_((1-y))N_(y))  (2b)

where each subscript denotes the atomic ratio specified below, witheither of m and n possibly being 0.

0≦k≦l-m-n

0<(m+n)≦0.2

0.5≦y≦1

The hard coating film of laminate type mentioned above is obtained byrepeating alternately several times a first step of forming a layer ofnitride or carbonitride (C/N atomic ratio being from 0.3/0.7 to 0/1), 1to 80 nm in thickness, by ion-plating or sputtering with a targetrepresented by the formula (1c) or (1d) below and a second step offorming a layer of nitride or carbonitride (C/N atomic ratio being from0.5/0.5 to 0/1), 1 to 80 nm in thickness, by ion-plating or sputteringwith a target represented by the formula (2c) or (2d) below.

(Cr_((1-a))Al_(a))  (1c)

(Cr_((1-a-b-c))Al_(a)Si_(b)B_(c))  (1d)

(Zr_((1-k))Hf_(k))  (2c)

(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))  (2d)

where each subscript denotes the atomic ratio specified below, witheither of b and c possibly being 0 and either of m and n possibly being0.

0.2≦a≦0.8

0<(b+c)≦0.2

0≦k≦1 (for the formula 2c) or

0≦k≦1-m-n (for the formula 2d)

0<(m+n)≦0.2

At least either (particularly both) of the layer of a first kind and thelayer of a second kind should preferably possess the cubic crystalstructure.

The hard coating film according to the present invention is notrestricted to that of laminate type; it may be a hard coating film whichhas a composition represented by the formula (3a) or (3b) below.

(Cr_((1-p-q-r))Al_(p)Zr_(q)Hf_(r))(C_((1-z))N_(z))  (3a)

where each subscript denotes the atomic ratio specified below, witheither of q and r possibly being 0.when p≦0.5:

0.2≦p<0.5

0.2≦(q+r)≦0.5

0.05≦(1-p-q-r)

0.5≦z≦1

when p≧0.5:

0.5≦p≦0.7

0.05≦(q+r)≦0.25

0.15≦(1-p-q-r)

0.5≦z≦1

(Cr_((1-p-q-r-s-t))Al_(p)Zr_(q)Hf_(r)Si_(s)B_(t))(C_((1-z))N_(z))  (3b)

where each subscript denotes the atomic ratio specified below, witheither of q and r possibly being 0 and either of s and t possibly being0.when p<0.5:

0.2≦p<0.5

0.2≦(q+r)≦0.5

0<(s+t)≦0.2

0.05≦(1-p-q-r-s-t)

0.5≦z≦1

when p≧0.5

0.5≦p≦0.7

0.05≦(q+r)≦0.25

0<(s+t)≦0.2

0.15≦(1-p-q-r-s-t)

0.5≦z≦1

The hard coating film mentioned above is obtained by forming a layer ofnitride or carbonitride (C/N atomic ratio being from 0.5/0.5 to 0/1) byion-plating or sputtering with a target represented by the formula (3c)or (3b) below.

(Cr_((1-p-q-r))Al_(p)Zr_(q)Hf_(r))  (3c)

where each subscript denotes the atomic ratio specified below, witheither of q and r possibly being 0.when p<0.5:

0.2≦p<0.5

0.2≦(q+r)≦0.5

0.05≦(1-p-q-r)

when p≧0.5:

0.5≦p≦0.7

0.05≦(q+r)≦0.25

0.15≦(1-p-q-r)

(Cr_((1-p-q-r-s-t))Al_(p)Zr_(q)Hf_(r)Si_(s)B_(t))  (3d)

where each subscript denotes the atomic ratio specified below, witheither of q and r possibly being 0 and either of s and t possibly being0.when p<0.5:

0.2≦p<0.5

0.2≦(q+r)≦0.5

0<(s+t)≦0.2

0.05≦(1-p-q-r-s-t)

when p≧0.5:

0.5≦p≦0.7

0.05≦(q+r)≦0.25

0<(s+t)≦0.2

0.15≦(1-p-q-r-s-t)

The hard coating film mentioned above should preferably possess thecubic crystal structure.

The hard coating film according to the present invention has a thicknessno smaller than 1000 nm regardless of whether it is of laminate type ornot.

EFFECT OF THE INVENTION

The hard coating film according to the present invention has improvedhigh-temperature characteristics because it is made from CrAl in itsnitride (CrAlN) or carbonitride (CrAlCN) form properly combined with Zrand/or Hf. The nitride and carbonitride will be collectively referred toas (carbo)nitride hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an example of the apparatus forfabricating the hard coating film according to the present invention.

FIG. 2 is a schematic diagram showing another example of the apparatusfor fabricating the hard coating film according to the presentinvention.

FIG. 3 is a schematic diagram showing further another example of theapparatus for fabricating the hard coating film according to the presentinvention.

The hard coating film according to the present invention is formed froma (carbo)nitride of CrAl properly combined with Zr and/or Hf. The firstembodiment is designed for a hard coating film of laminate typeconsisting of thin layers of a (carbo)nitride of CrAl and a(carbo)nitride of Zr and/or Hr. The second embodiment is designed for ahard coating film of single-layer type formed from a (carbo)nitride ofCrAl combined with Zr and/or Hf. (This hard coating film will bereferred to as a single-layered hard coating film hereinafter. The(carbo)nitride from which the single-layered hard coating film is formedwill be referred to as CrAlZrHf (carbo)nitride hereinafter.)(Carbo)nitrides of Zr and Hf have a larger negative free energy offormation than (carbo)nitrides of Ti and Cr. Therefore, a (carbo)nitrideof CrAl is improved in high-temperature stability, high-temperaturehardness, and wear resistance when it is laminated with or incorporatedwith a (carbo)nitride of Zr or Hf.

Incidentally, the (carbo)nitride of CrAl, the (carbo)nitride of Zrand/or Hf, and the (carbo)nitride of CrAlZrHf may also be incorporatedwith Si and/or B. The thus added Si and B further improve the hardcoating film in oxidation resistance and contribute to the formation offine crystal grains in the hard coating film.

The following is a detailed description of the hard coating filmaccording to the present invention.

<Hard Coating Film of Laminate Type>

The hard coating film of laminate type according to the presentinvention consists of more than one layer of a first kind formed from a(carbo)nitride of CrAl represented by the formula (1a) below and morethan one layer of a second kind formed from a (carbo)nitride of Zrand/or Hf represented by the formula (2a) below, the layers being placedalternately one over another.

(Cr_((1-a))Al_(a))(C_((1-x))N_(x))  (1a)

(Zr_((1-k))Hf_(k))(C_((1-y))N_(y))  (2a)

where each subscript denotes the atomic ratio specified below.

0.2≦a≦0.8

0.7≦x≦1

0≦k≦1

0.5≦y≦1

The layer of a first kind is formed from a (carbo)nitride of CrAlrepresented by the formula (1a). Al in this compound contributes tooxidation resistance and hardness. The atomic ratio (a) of Al in theformula (1a) should be no smaller than 0.2, preferably no smaller than0.3, more preferably no smaller than 0.4. Usually, an increasing atomicratio of Al is responsible for improved oxidation resistance. However,Al in an excess amount changes the crystal structure of the hard coatingfilm from cubic to hexagonal. The cubic structure (or rock saltstructure or NaCl structure) leads to the high hardness phase. (It willbe referred to as B1 structure hereinafter.) The hexagonal structure (orwurtzite structure or ZnS structure) leads to the comparatively lowhardness phase. (It will be referred to as B4 structure hereinafter.)Therefore, the atomic ratio (a) of Al should be no larger than 0.8,preferably no larger than 0.7.

The atomic ratio (x) of N in the formula (1a) for the layer of a firstkind should be no smaller than 0.7, preferably no smaller than 0.8, morepreferably no smaller than 0.9. A decrease in the atomic ratio (x) of Nleads to an increase in the atomic ratio of C, resulting in an unstablecompound of AlC₃.

The composition represented by the formula (2a) for the layer of asecond kind may contain (carbo)nitrides of Zr and/or Hf in any atomicratio because Zr and Hf have mutually similar properties. In otherwords, the atomic ratio (k) of Hf in the formula 2a may take any valuefrom 0 to 1, preferably 0.1 to 0.8, more preferably 0.2 to 0.5.

The composition for the layer of a second kind contains C which formshigh-hardness compounds such as ZrC and HfC, thereby making the coatingfilm hard. However, with an excessively large atomic ratio (1-y) of C,the resulting coating film will be poor in oxidation resistance. In thisspecification, the atomic ratio (1-y) of C is indirectly specified bythe atomic ratio (y) of N. The atomic ratio (y) of N should be from 0.5to 1, preferably from 0.6 to 1.

The layer of a first kind should have a thickness of about 1 to 80 nm.In order for it to contribute to hardness, it should have an adequatethickness no smaller than 5 nm, particularly no smaller than 20 nm. Whenit is excessively thick, the layer of a second kind will be too thin tocontribute to the high temperature stability of the hard coating film.Therefore, it should have a thickness no smaller than 80 nm, preferablyno smaller than 70 nm, more preferably no smaller than 60 nm.

The layer of a second kind should have a thickness of about 1 to 80 nm.It is characterized by its thermodynamic stability, and it stabilizesthe layer of a first kind which easily changes in crystal structure athigh temperatures. It decreases in this stabilizing effect if it has anexcessively small thickness. A desired thickness is no smaller than 2nm, particularly no smaller than 10 nm. The hard coating film willdecrease in hardness if the layer of a second kind has an excessivelylarge thickness because it is less hard than the layer of a first kind.Therefore, a desired thickness is no larger than 50 nm, particularly nolarger than 35 nm.

The layer of a first kind and the layer of a second kind may have athickness of T₁ and a thickness of T₂, respectively, such that thedifference between T₁ and T₂ is smaller than 0, preferably no smallerthan 0, more preferably about 5 to 50, particularly about 10 to 40. Ifthe layer of a first kind is thicker than the layer of a second kind(that is, the difference (T₁−T₂) is no smaller than 0), the resultinghard coating film will have improved hardness because the former (whichis harder than the latter) accounts for a larger portion.

The hard coating film consists of more than one layer of a first kindand more than one layer of a second kind, the layers being placedalternately one over another as many times as steps of lamination. Thelayers of a first kind may be replaced at least partly (entirely inparticular) by layers additionally containing Si and/or B. The layer ofa first kind additionally containing Si and/or B is identical with theordinary layer of a first kind represented by the formula (1a), exceptthat it is represented by the formula (1b) below (in which B may combinewith the carbonitride or form borides with Cr, Al, and Si).

(Cr_((1-a-b-c))Al_(a)Si_(b)B_(c))(C_((1-x))N_(x))  (1b)

where each subscript denotes the atomic ratio specified below, witheither of b and c possibly being 0, and a being defined as in theformula (1a).

0<(b+c)≦0.2

The additional Si and/or B form the Si—N bond or B—N bond at the grainboundary, thereby suppressing crystal growth and giving rise to finecrystals, which leads to improved hardness. They also contribute tooxidation resistance (although not yet elucidated). An adequate amountof (b+c) should be no less than 0.02, preferably no less than 0.05. Anexcess amount of Si and/or B allows hexagonal crystals to dominate. Theupper limit of the amount of (b+c) should be 0.2, preferably 0.15, morepreferably 0.1.

Either or both of Si and B may be added. Therefore, either of thesubscripts b and c may be 0. Since Si is superior to B in oxidationresistance, it is desirable to add Si more than B if oxidationresistance is important (or it is more desirable to add Si only). On theother hand, since B forms the B—N bond for lubrication, it is desirableto add B more than Si if lubricity is important (or it is more desirableto add B only).

The layers of a second kind may be replaced at least partly (entirely inparticular) by layers additionally containing Si and/or B. The layer ofa second kind additionally containing Si and/or B is identical with theordinary layer of a second kind represented by the formula (2a), exceptthat it is represented by the formula (2b) below (in which B may combinewith the carbonitride or form borides with Zr, Hf, and Si).

(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))(C_((1-y))N_(y))  (2b)

where each subscript denotes the atomic ratio specified below, witheither of m and n possibly being 0.

0≦k≦1-m-n

0<(m+n)≦0.2

The range of “m+n” is specified for the same reason as the range of“b+c” mentioned above. Either of m and n may be 0 for the same reason asmentioned above for b and c. The desired range of K is the same as thatin the formula 2a.

Either or both of the layer of a first kind and the layer of a secondkind may be replaced by the layer containing Si and/or B mentionedabove.

It is desirable that at least either (preferably both) of the layer of afirst kind and the layer of a second kind (both of them may contain Siand/or B) exhibit the cubic crystal structure, which is harder than thehexagonal crystal structure.

The hard coating film of laminate type mentioned above is obtained byrepeating alternately several times a first step of forming the layer ofa first kind (which may or may not contain Si and/or B) and a secondstep of forming the layer of a second kind (which may or may not containSi and/or B). The first and second steps may be accomplished by anyknown method such as physical vapor deposition (PVD) and chemical vapordeposition (CVD). PVD (including sputtering, ion plating, electron beamdeposition, and hollow cathode deposition) is desirable for good layeradhesion.

The first and second steps by PVD employ specific targets to form thelayers of a first kind and a second kind. Each target contains elementsthat constitute the layers. For example, the first step employs thetarget having a composition represented by the formula (1c) or (1d)below to form the layer of (carbo)nitride having the C/N atomic ratio offrom 0.3/0.7 to 0/1 and having a thickness of 1 to 80 nm. The secondstep employs the target having a composition represented by the formula(2c) or (2d) below to form the layer of (carbo)nitride having the C/Natomic ratio of from 0.5/0.5 to 0/1 and having a thickness of 1 to 80nm.

(Cr_((1-a))Al_(a))  (1c)

(Cr_((1-a-b-c))Al_(a)Si_(b)B_(c))  (1d)

(Zr_((1-k))Hf_(k))  (2c)

(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))  (2d)

where each subscript denotes the atomic ratio as specified above for theformulas (1a), (1b), (2a), and (2b) above.

Preferred film-forming methods are sputtering and ion plating, in whichthe rate of evaporation of elements in the target does not greatlydepend on their melting point. Film forming by electron beam depositionand hollow cathode deposition present difficulties in controlling theamount of evaporation of each element in the target.

Ion plating (particularly arc ion plating) excels sputtering(particularly unbalance magnetron sputtering (UBMS)) in film formingrate. However, sputtering is superior to ion plating in easydischarging, easy thickness control, and infrequent target breakage.These characteristics may be used to select an adequate film formingmethod. For example, sputtering is suitable for deposition that employsa target containing Zr and/or Hf because ion plating presentsdifficulties with discharging. Except for the foregoing, ion plating isrecommended for better fabrication efficiency.

The method for forming the hard coating film of laminate type bysputtering (particularly UBMS) or ion plating (particularly arc ionplating) will be described in more detail with reference to theaccompanying drawings.

FIG. 1 is a schematic diagram showing an example of the apparatus forfabricating the hard coating film according to the present invention.The apparatus 11 shown in FIG. 1 has two mutually different evaporationsources 21 and 22 (for sputtering) positioned in the same direction. Theevaporation sources 21 and 22 each have the magnetic field generatingmechanism 101 behind them, so that they form the film in their frontside. There is a rotary table 41 in front of the evaporation sources 21and 22. Onto the rotary table 41 is attached a substrate 51. The firstevaporation source 21 is the target (1c) or (1d) mentioned above, andthe second evaporation source 22 is the target (2c) or (2d). Thesetargets are allowed to evaporate in a film-forming gas, which includesan N-containing gas (such as nitrogen), a mixture of N-containing gasand C-containing gas (such as methane), and the foregoing gas dilutedwith an inert gas (such as argon). As the rotary table 41 turns, thesubstrate 51 faces alternately the first evaporation source 21 and thesecond evaporation source 22. In this way the layer of a first kind andthe layer of a second kind are alternately formed one over another onthe substrate 51. Thus there is obtained the hard coating film.

FIG. 2 is a schematic diagram showing another example of the apparatusfor fabricating the hard coating film according to the presentinvention. The apparatus 12 shown in FIG. 2 has two mutually differentevaporation sources 23 (arc type) and 24 (sputtering type) facing thesubstrate 51. The evaporation sources 23 and 24 are separated from thesubstrate 51 by the shutters 61 and 62 placed between them. The shutters61 and 62 shut out the vapors 33 and 34 from the evaporation sources 23and 24. One evaporation source is the target (1c) or (1d) mentionedabove, and the other evaporation source is the target (2c) or (2d)mentioned above. These targets are allowed to evaporate in afilm-forming gas, which includes an N-containing gas, a mixture ofN-containing gas and C-containing gas, and the foregoing gas dilutedwith an inert gas. During evaporation, the shutters 61 and 62 are openedand closed alternately. In this way the layer of a first kind and thelayer of a second kind are alternately formed one over another on thesubstrate 51. Thus there is obtained the hard coating film.

The same function as shutter opening and closing may be accomplished byturning on and off the discharging of the evaporation sources tofabricate the hard coating film.

The apparatuses 11 and 12 shown in FIGS. 1 and 2 may have two or moreevaporation sources. In such a case, both of the targets (1c) and (1d)may be used as the evaporation sources for the layer of a first kind,and the targets (2c) and (2d) may be used as the evaporation sources forthe layer of a second kind.

Also, the apparatuses 11 and 12 shown in FIGS. 1 and 2 may have eithersputtering sources or arc sources as the evaporation sources. In apreferred embodiment, the targets (1c) and (2c) should be discharged byarc ion plating, and the targets (1d) and (2d) should be discharged bysputtering.

Incidentally, the apparatuses shown in FIGS. 1 and 2 permit film formingon a flat substrate but involves difficulties in film forming on arod-like substrate. Their ability depends on the shape of the substrate.The apparatus shown in FIG. 2 suffers from low film forming efficiencybecause one evaporation source remains idle while the other evaporationsource is in use. Therefore, it is recommended to use the apparatusshown in FIG. 3 to overcome such disadvantages.

The apparatus 13 shown in FIG. 3 consists of a vacuum chamber 8 and arotary plate 72 placed therein. The rotary plate 72 has four rotarytables 71 which are symmetrically arranged. On each rotary table 71 aremounted substrates 51. Around the rotary plate 72 are arranged the firstevaporation sources 25 and 26 (of arc type) and the second evaporationsources 27 and 28 (of sputtering type). These evaporation sources arearranged such that the first pair and the second pair adjoinalternately.

One set of the evaporation sources consists of the targets (1c) and/or(1d) and the other set of the evaporation sources consists of thetargets (2c) and/or (2d). These targets are allowed to evaporate in afilm-forming gas, which includes an N-containing gas, a mixture ofN-containing gas and C-containing gas, and the foregoing gas dilutedwith an inert gas. As the rotary plate 72 and the rotary tables 71 turn,the substrate 51 faces alternately the first set of evaporation sources25 and 26 and the second set of evaporation sources 27 and 28. In thisway the layer of a first kind and the layer of a second kind arealternately formed one over another on the substrate 51. Thus there isobtained the hard coating film. The apparatus shown in FIG. 3 is veryefficient because all the evaporation sources work at all times. Thethickness of individual layers can be controlled by adjusting therotating speed of the substrate and the power supplied to theevaporation sources.

The apparatus shown in FIG. 3 has the magnetic field generator 101 whichseparates the magnetic field of the arc evaporation sources 25 and 26and the magnetic field 112 of the sputtering evaporation sources 27 and28 from each other. There may be a situation in which the magneticfields 111 and 112 join together. In the case where the magnetic fields111 and 112 do not join each other, those electrons released from theevaporation sources 25, 26, 27, and 28 are introduced not only to thesubstrate 51 but also to the chamber 8 which functions as the anode. Bycontrast, in the case where the magnetic fields 111 and 112 jointogether, the magnetic field (or magnetic flux) in the chamber 8 isclosed and those electrons released from the evaporation sources 25, 26,27, and 28 are trapped in the closed magnetic field. This leads toefficient film forming and improved film properties because of increaseddirectivity.

The apparatus shown in FIG. 3 (or FIG. 1) is of a rotary type; however,it may be of any type so long as it permits the substrate 51 to pass thefront of the evaporation source. A possible example may be such that theevaporation sources are linearly arranged and the substrate reciprocatesin front of them.

<Hard Coating Film of Single-Layer Type>

The hard coating film according to the present invention is not limitedto that of laminate type mentioned above. A hard coating film ofsingle-layer type fabricates the same effect as a hard coating film oflaminate type if it is formed from a (carbo)nitride of CrAlZrHf (whichis obtained by addition of Zr and/or Hf to a (carbo)nitride of CrAl). Tobe concrete, the hard coating film of single-layer type has acomposition represented by the formula (3a) below.

(Cr_((1-p-q-r))Al_(p)Zr_(q)Hf_(r))(C_((1-z))N_(z))  (3a)

where each subscript denotes the atomic ratio specified below, witheither of q and r possibly being 0.when p<0.5:

0.2≦p<0.5

0.2≦(q+r)≦0.5

0.05≦(1-p-q-r)

0.5≦z≦1

when p≧0.5:

0.5≦p≦0.7

0.05≦(q+r)≦0.25

0.15≦(1-p-q-r)

0.5≦z≦1

In the formula (3a) above, the subscript p denotes the atomic ratio ofAl. The value of p should be larger than the minimum value because Al isessential for hardness and oxidation resistance as in the case of thehard coating film of laminate type. However, with an excessively largevalue of p, the resulting hard coating film tends to assume thehexagonal structure (which is soft). Therefore, the atomic ratio of Alshould be no smaller than 0.2, preferably no smaller than 0.25, morepreferably no smaller than 0.3, and no larger than 0.7, preferably nolarger than 0.65, more preferably no larger than 0.6.

In the formula (3a) above, the total atomic ratio (q+r) for Zr and Hfand the atomic ratio (1-p-q-r) for Cr range differently depending on theatomic ratio (p) for Al. If the atomic ratio (p) for Al is smaller than0.5, it is necessary to add Zr and/Hf sufficiently to make up for therole of Al (for hardness and oxidation resistance). On the other hand,if the atomic ratio (p) for Al is no smaller than 0.5, the amount of Zrand/or Hf should be reduced because excess Zr and/or Hf changes thecrystal structure into the hexagonal one. The atomic ratio (1-p-q-r) forCr is determined according to the total atomic ratio (q+r) for Zr and Hfand the film characteristics required. The following rules apply to thetotal atomic ratio (q+r) for Zr and Hf and the atomic ratio (1-p-q-r)for Cr.

(1) If the atomic ratio (p) for Al is smaller than 0.5. The total atomicratio (q+r) for Zr and Hf should be no smaller than 0.2, preferably nosmaller than 0.23, more preferably no smaller than 0.25, and no largerthan 0.5, preferably no larger than 0.47, more preferably no larger than0.45.The atomic ratio (1-p-q-r) for Cr should be no smaller than 0.05,preferably no smaller than 0.1, more preferably no smaller than 0.15.(2) If the atomic ratio (p) for Al is no smaller than 0.5. The totalatomic ratio (q+r) for Zr and Hf should be no smaller than 0.05,preferably no smaller than 0.08, more preferably no smaller than 0.1,and no larger than 0.25, preferably no larger tan 0.22, more preferablyno larger than 0.2.The atomic ratio (1-p-q-r) for Cr should be no smaller than 0.15,preferably no smaller than 0.15, more preferably no smaller than 0.2.

It is possible to add either or both of Zr and Hf regardless of therange of the atomic ratio (p) for Al. Therefore, either of q and r maybe 0.

The atomic ratio (z) for N should be from 0.5 to 1, preferably from 0.8to 1 regardless of the range of the atomic ratio (p) for Al. The atomicratio (z) for N is limited to the specific range for the same reason asthe hard coating film of laminate type.

The hard coating film of single-layer type may additionally contain Siand/or B in the same way as the hard coating film of laminate typementioned above. The hard coating film of single-layer type containingSi and/or B has a composition represented by the formula (3b) below, inwhich B may form a carbonitride or B may also form a boride with Cr, Al,Zr, Hf, and Si.

(Cr_((1-p-q-r-s-t))Al_(p)Zr_(q)Hf_(r)Si_(s)B_(t))(C_((1-z))N_(z))  (3b)

where each subscript denotes the atomic ratio specified below, witheither of q and r possibly being 0 and either of s and t possibly being0.when p<0.5:

0.2≦p<0.5

0.2≦(q+r)≦0.5

0<(s+t)≦0.2

0.05≦(1-p-q-r-s-t)

0.5≦z≦1

when p≧0.5:

0.5≦p≦0.7

0.05≦(q+r)≦0.25

0<(s+t)≦0.2

0.15≦(1-p-q-r-s-t)

0.5≦z≦1

The atomic ratio (p) for Al, the total atomic ratio (q+r) for Zr and Hf,and the atomic ratio (z) for N are specified for the same reason as theformula (3a) above. The atomic ratio (1-p-q-r-s-t) for Cr is specifiedfor the same reason as the atomic ratio (1-p-q-r) for Cr in the formula(3a) above. Either of s and t may be 0 for the same reason as b and cmentioned above.

The hard coating film of single-layer type may also be fabricated in thesame way as the hard coating film of laminate type mentioned above. Forexample, it may be formed by chemical vapor deposition (CVD) or physicalvapor deposition (PVD), particularly sputtering and ion plating (arc ionplating).

The hard coating film of single-layer type may be formed by PVD from thetarget represented by the formula (3c) or (3d) below which gives a(carbo)nitride layer having an C/N atomic ratio of from 0.5/0.5 to 0/1.

(Cr_((1-p-q-r))Al_(p)Zr_(q)Hf_(r))  (3c)

(Cr_((1-p-q-r-s-t))Al_(p)Zr_(q)Hf_(r)Si_(s)B_(t))  (3d)

where each subscript denotes the same values as defined for the formula(3a) and (3b) above.

The hard coating film of single-layer type should preferably have thecubit crystal structure as in the case of the hard coating film oflaminate type mentioned above.

According to the present invention, the hard coating film (of bothlaminate type and single-layer type) should have a thickness no smallerthan 1000 nm, preferably no smaller than 2000 nm, and no larger than10000 nm, preferably no larger than 5000 nm.

The hard coating film of the present invention has greatly improvedhigh-temperature characteristics because of the combination of(carbo)nitride of CrAl (represented by CrAlCN and CrAlN) and Zr and/orHf.

EXAMPLES

The invention will be described in more detail with reference to thefollowing examples, which are not intended to restrict the scopethereof. Various changes and modifications may be made in the presentinvention without departing from the spirit and scope thereof.

In the following experiment examples, the hard coating film was formedon three kinds of substrates specified below.

(1) Mirror-polished tip of cemented carbide (for examination of filmcomposition, crystal structure, and film hardness)(2) Ball-nose end mill of cemented carbide, 10 mm in diameter,two-blade, (for examination of wear width)(3) Platinum foil, 30×5×0.1 mmt, (for examination of oxidation startingtemperature)

The samples of hard coating film were tested for characteristicproperties in the following manner.

<Composition of Hard Coating Film>

The composition (metallic elements) of the hard coating film wasquantitatively analyzed by EDX (energy dispersive X-ray fluorescencespectroscopy) under the following conditions.

Accelerating voltage: 20 kVWD (work distance): 15 mmMeasuring time (live): 60 seconds, with ZAF correction

<Crystal Structure>

The samples of hard coating film were examined for X-ray diffractionpeaks by X-ray diffractometry (θ-2θ) method, CuK α line, at 40 kV and 40mA) using an X-diffraction apparatus made by Rigaku Denki. The peak at2θ=37.78° corresponds to the (111) plane of the cubic crystal, the peakat 2θ=43.9° corresponds to the (200) plane of the cubic crystal, and thepeak at 2θ=63.8° corresponds to the (220) plane of the cubic crystal.The peak at 2θ=32°-33° corresponds to the (100) plane of the hexagonalcrystal, the peak at 2θ=48°-50° corresponds to the (102) plane of thehexagonal crystal, and the peak at 2θ=57°-58° corresponds to the (110)plane of the hexagonal crystal. The intensity of each peak was measured,and the crystal structure index (X) was calculated according to theformula (4) below to determine the crystal structure of the hard coatingfilm according to the following criteria.

$\begin{matrix}{X = \frac{{{IB}(111)} + {{IB}(200)} + {{IB}(220)}}{\begin{matrix}{{{IB}(111)} + {{IB}(200)} + {{IB}(220)} +} \\{{{IH}(100)} + {{IH}(102)} + {{IH}(110)}}\end{matrix}}} & (4)\end{matrix}$

In the formula (4), IB(111), IB(200), and IB(220) denote the intensityof peak of each plane of the cubic crystals, and IH(100), IH(102), andIH(110) denote the intensity of peak of each plane of the hexagonalcrystals. An index (X) larger than 0.9 represents the cubic crystalstructure (indicated by B1 in the following tables).

An index (X) no smaller than 0.1 and smaller than 0.9 represents themixed crystal structure (indicated by B1+B4 in the following tables).An index (X) smaller than 0.1 represents the hexagonal crystal structure(indicated by B4 in the following tables).

<Hardness>

The samples were tested for hardness by using a micro-vickers hardnessmeter, with a load of 0.25 N applied for 15 seconds.

<Oxidation Starting Temperature>

The coated platinum foil (obtained in the following experiment example)was heated in dry air at a rate of 5° C./min and examined for weightchange by using a thermo-balance. The oxidation starting temperature wasdetermined from the weight increase curve.

<Wear Width>

The hard film-coated end mill of cemented carbide (10 mm in diameter,two-flutes), which was obtained in the following experiment example, wasused to cut SKD61 hardened steel (HRC50) under the following conditions.After cutting, the blade was observed under an optical microscope tomeasure the wear width at the boundary between rake face and flank face.

Cutting speed: 220 m/minFeed: 0.05 mm/bladeCutting depth: 4.5 mm

Axial cut: 1 mm

Others: dry cutting, air blowing

Experiment Example 1

The apparatus shown in FIG. 3 was used in which the arc evaporationsources 25 and 26 are provided with targets of Cr and Al (whosecomposition is almost identical with that of the first layer shown inTable 1) and the sputtering evaporation sources 27 and 28 are providedwith targets of Zr and Hf (whose composition is almost identical withthat of the second layer shown in Table 1). A substrate 51 (tip,ball-nose end mill, or platinum foil), which had been degreased andcleaned with ethanol, was attached to the rotary table 71, and thechamber 8 was evacuated. The system was heated to about 500° C. with aheater (not shown) and the substrate 51 was cleaned with argonintroduced into the system, with the rotary plate 72 and the rotarytable 71 turning. The film-forming gas (specified below) was introducedand the evaporation sources 25, 26, 27, and 28 were activated to form ahard coating film of laminate type. This procedure was continued untilthe hard coating film grew to a thickness of 3 μm.

Film-Forming Gas:

A mixture of Ar and N₂, or a mixture of Ar, N₂ and CH₄

Total pressure: 2.6 Pa

Partial pressure of reaction gas (N₂+CH₄): 1.3 Pa

The thicknesses of the layers of a first kind and a second kind werecontrolled by adjusting electric power applied to the evaporation sourceand the period of rotation of the substrate 51.

The hard coating film thus obtained exhibited the physical propertiesshown in Table 1.

TABLE 1 Layer of a first kind Layer of a second kind Film OxidationComposition of film Thick- Crystal Composition of film Thick- Crystalhard- starting Wear Cr Al C N Ness struc- Zr Hf C N ness struc- No. ofness temp. width No. (1 − a) (a) (1 − x) (x) (nm) ture (1 − k) (k) (1 −y) (y) (nm) ture layers (HV) (° C.) (μm) i Ti_(0.5)Al_(0.5)N 3000 B1 — 12500 850 * ii TiCN 3000 B1 — 1 2800 650 ** iii Cr_(0.35)Al_(0.65)N 3000B1 — 1 2900 1000 100 1 1 0 0 1 50 B1 1 0 0 1 20 B1 42 2800 650 105 20.85 0.15 0 1 50 B1 1 0 0 1 20 B1 42 2850 1000 100 3 0 1 0 1 50 B4 1 0 01 20 B1 42 2700 1200 120 4 0.37 0.63 0.4 0.6 50 B1 0.8 0.2 0.3 0.7 20 B142 3250 1000 55 5 0.37 0.63 0.7 0.3 50 B1 0.8 0.2 0.1 0.9 20 B1 42 2850950 95 6 0.37 0.63 0.75 0.25 50 B1 0.8 0.2 0.25 0.75 20 B1 42 2700 90085 7 0.37 0.63 0 1 0.5 B1 0.85 0.15 0 1 30 B1 98 2900 850 90 8 0.37 0.630 1 30 B1 0.8 0.2 0.1 0.9 0.2 B1 99 2900 1000 100 9 0.4 0.6 0 1 100 B10.9 0.1 0 1 130 B1 13 2900 1050 85 10 0.4 0.6 0 1 200 B1 0.85 0.15 0 150 B1 12 2800 1000 90 11 0.7 0.3 0 1 50 B1 1 0 0 1 20 B1 42 3000 1050 6512 0.5 0.5 0 1 50 B1 1 0 0 1 20 B1 42 3200 1100 45 13 0.34 0.66 0 1 50B1 1 0 0 1 20 B1 42 3200 1150 30 14 0.2 0.8 0 1 50 B4 1 0 0 1 20 B1 422950 1200 58 15 0.4 0.6 0 1 50 B1 0.8 0.2 0 1 20 B1 42 3150 1200 40 160.4 0.6 0 1 50 B1 0.55 0.45 0 1 20 B1 42 3100 1200 37 17 0.4 0.6 0 1 50B1 0.25 0.75 0 1 20 B1 42 3150 1150 41 18 0.4 0.6 0 1 50 B1 0.05 0.95 01 20 B1 42 3200 1200 43 19 0.37 0.63 0.2 0.8 50 B1 0.8 0.2 0.3 0.7 20 B142 3250 1050 49 20 0.4 0.6 0.1 0.9 5 B1 1 0 0 1 10 B1 200 3100 1100 4521 0.37 0.65 0 1 20 B1 0.4 0.6 0 1 25 B1 66 3300 1200 40 22 0.35 0.65 01 25 B1 0.7 0.3 0 1 35 B1 50 3250 1150 38 23 0.33 0.67 0 1 30 B1 1 0 0 115 B1 66 3200 1100 36 * died after 50 m, ** died after 20 m.

The samples Nos. 11 to 23 in Table 1 correspond to the hard coating filmof laminate type according to the present invention. They are superiorto the samples Nos. i to iii of conventional hard coating film (shown inTable 1) in hardness, oxidation starting temperature, and wear width.

Experiment Example 2

The same procedure as Experiment Example 1 was repeated except that thearc evaporation sources 25 and 26 were provided with targets ofCr.Al.Si.B (having almost the same composition as the layer of a firstkind shown in Table 2) and the sputtering evaporation sources 27 and 28were provided with targets of Zr.Hf.Si.B (having almost the samecomposition as the layer of a second kind shown in Table 1).

The hard coating film thus obtained exhibited the physical propertiesshown in Table 2.

TABLE 2 Layer of a first kind Layer of a second kind Composition of filmComposition of film Cr Thick- Zr (1 − a − Al Si B C N Ness Crystal (1 −k − Hf Si No. b − c) (a) (b) (c) (1 − x) (x) (nm) Structure m − n) (k)(m) i Ti_(0.5)Al_(0.5)N 3000 B1 — ii TiCN 3000 B1 — iiiCr_(0.35)Al_(0.65)N 3000 B1 — 1 0.4 0.35 0.25 0 0 1 40 B4 1 0 0 2 0.40.54 0.06 0 0 1 40 B1 0 0.73 0 3 0.34 0.66 0 0 0 1 40 B1 1 0 0 4 0.40.57 0.03 0 0 1 40 B1 1 0 0 5 0.4 0.54 0.06 0 0 1 40 B1 1 0 0 6 0.4 0.450.15 0 0 1 40 B1 + B4 1 0 0 7 0.4 0.54 0.06 0 0 1 40 B1 0.96 0 0 8 0.40.54 0.06 0 0 1 40 B1 0.5 0.42 0 9 0.4 0.54 0.06 0 0 1 40 B1 0.85 0 0Layer of a second kind Film Oxidation Composition of film Thick- hard-starting Wear B C N Ness Crystal No. of ness temp. width No. (n) (1 − y)(y) (nm) Structure layers (HV) (° C.) (□m) i — 1 2500 850 * ii — 1 2800650 ** iii — 1 2900 1000 100 1 0 0 1 20 B1 50 2900 1300 68 2 0.27 0 1 20B4 50 2800 1100 78 3 0 0 1 20 B1 50 3200 1150 30 4 0 0 1 20 B1 50 32001250 25 5 0 0 1 20 B1 50 3250 1250 23 6 0 0 1 20 B1 50 3100 1300 35 70.04 0 1 30 B1 50 3150 1200 35 8 0.08 0 1 20 B1 50 3250 1250 37 9 0.15 01 20 B1 50 3250 1250 41 * died after 50 m, ** died after 20 m.

The samples Nos. 3 to 9 in Table 2 correspond to the hard coating filmof laminate type according to the present invention. They are superiorto the samples Nos. i to iii of conventional hard coating film (shown inTable 1) in hardness, oxidation starting temperature, and wear width.

Experiment Example 3

The same procedure as Experiment Example 1 was repeated except that thearc evaporation sources 25, 26, 27, and 28 were provided with targets ofCr.Al.Zr.Hf (having almost the same composition as shown in Table 3).(Sputtering evaporation sources were not used.) Deposition was carriedout by using N₂ gas (having a total pressure of 4 Pa) or a mixture gasof N₂ and CH₄ (having a partial pressures of 2.7 Pa and 1.3 Pa,respectively for N₂ and CH₄, and a total pressure of 4 Pa).

The hard coating film thus obtained exhibited the physical propertiesshown in Table 3.

TABLE 3 Composition of film Cr Film Oxidation Wear (1 − p − Al Zr Hf C NCrystal hardness starting width No. q − r) (p) (q) (r) (1 − z) (z)structure (HV) temp. (° C.) (μm) i Ti_(0.5)Al_(0.5)N B1 2500 850 * iiTiCN B1 2800 650 ** iii Cr_(0.35)Al_(0.65)N B1 2900 1000 100 1 0.8 0 0.20 0 1 B1 2700 650 105 2 0.75 0.1 0.15 0 0 1 B1 2750 700 98 3 0.4 0.350.05 0.2 0 1 B1 3000 1050 65 4 0.2 0.35 0.2 0.25 0 1 B1 3200 1100 45 50.3 0.4 0.3 0 0 1 B1 3100 1150 47 6 0 0.5 0 0.5 0 1 B1 + B4 2950 850 967 0.05 0.65 0.2 0.1 0 1 B1 + B4 2800 950 80 8 0.05 0.55 0.4 0 0 1 B1 +B4 2750 900 90 9 0.15 0.8 0 0.05 0 1 B1 + B4 2800 1100 100 10 0.2 0.650.15 0 0 1 B1 3200 1100 45 11 0.25 0.6 0 0.15 0.2 0.8 B1 3150 1150 50 *died after 50 m, ** died after 20 m.

The samples Nos. 3 to 5 and Nos. 10 and 11 in Table 3 correspond to thehard coating film according to the present invention. They are superiorto the samples Nos. i to iii of conventional hard coating film (shown inTable 3) in hardness, oxidation starting temperature, and wear width.

Experiment Example 4

The same procedure as Experiment Example 3 was repeated except that theevaporation source was provided with a target of Cr.Al.Zr.Hf.Si.B(having almost the same composition as shown in Table 4).

The hard coating film thus obtained exhibited the physical propertiesshown in Table 4.

TABLE 4 Film composition Cr Film Oxidation Wear (1 − p − q − Al Zr Hf SiB C N Crystal hardness starting width No. r − s − t) (p) (q) (r) (s) (t)(1 − z) (z) structure (HV) temp. (° C.) (μm) i Ti_(0.5)Al_(0.5)N B1 2500850 * ii TiCN B1 2800 850 ** iii Cr_(0.35)Al_(0.65)N B1 2900 1000 100 10.12 0.3 0.1 0.2 0 0.28 0 1 B1 + B4 2900 1200 78 2 0.2 0.35 0.16 0.25 00.04 0 1 B1 3200 1100 45 3 0.15 0.35 0.15 0.25 0 0.1 0 1 B1 3250 1150 424 0.15 0.35 0.1 0.25 0 0.15 0 1 B1 3200 1200 48 5 0.32 0.4 0.15 0.050.03 0.05 0.1 0.9 B1 3250 1250 37 6 0.13 0.5 0.1 0 0.27 0 0 1 B1 + B42900 1300 67 7 0.2 0.6 0.15 0 0.05 0 0 1 B1 3200 1200 35 8 0.2 0.6 0.120 0.08 0 0 1 B1 3250 1300 32 * died after 50 m, ** died after 20 m.

The samples Nos. 2 to 5 and Nos. 7 and 8 in Table 4 correspond to thehard coating film according to the present invention. They are superiorto the samples Nos. i to iii of conventional hard coating film (shown inTable 4) in hardness, oxidation starting temperature, and wear width.

The hard coating film according to the present invention excels inhardness, oxidation starting temperature, wear width (for high-speedcutting in a dry state), and high-temperature characteristics. It issuitable for coating of cutting tools and dies (such as high speed toolsteel (SKH51, SKD11, SKD61, cemented carbide, and other ferroussubstrates). Coated substrates are useful as cutting tools and dieshaving outstanding hardness and oxidation resistance.

1. A hard coating film of laminate type comprising: more than one layerof a first kind, each of which has a thickness of 1 to 80 nm and acomposition represented by the formula (1a) below,(Cr_((1-a))Al_(a))(C_((1-x))N_(x))  (1a) where 0.2≦a≦0.8, and 0.7≦x≦1;and more than one layer of a second kind, each of which has a thicknessof 1 to 80 nm and a composition represented by the formula (2a) below,(Zr_((1-k))Hf_(k))(C_((1-y))N_(y))  (2a), where 0≦k≦1, and 0.5≦y≦1,wherein the layers are placed alternately one over another.
 2. The hardcoating film of laminate type according to claim 1, wherein the morethan one layer of a first kind are replaced at least partly by layerseach having a thickness of 1 to 80 nm and a composition represented bythe formula (1b) below,(Cr_((1-a-b-c))Al_(a)Si_(b)B_(c))(C_((1-x))N_(x))  (1b), where0.2≦a≦0.8, 0<(b+c)≦0.2, 0.7≦x≦1, and either of b and c possibly is
 0. 3.The hard coating film of laminate type according to claim 1, wherein themore than one layer of a second kind are replaced at least partly bylayers each having a thickness of 1 to 80 nm and a compositionrepresented by the formula (2b) below,(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))(C_((1-y))N_(y))  (2b), where0≦k≦1-m-n, 0<(m+n)≦0.2, 0.5≦y≦1, and either of m and n possibly is
 0. 4.The hard coating film of laminate type according to claim 2, wherein themore than one layer of a second kind are replaced at least partly bylayers each having a thickness of 1 to 80 nm and a compositionrepresented by the formula (2b) below,(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))(C_((1-y))N_(y))  (2b), where0≦k≦1-m-n, 0<(m+n)≦0.2, 0.5≦y≦1, and either of m and n possibly is
 0. 5.A hard coating film of laminate type which is obtained by repeatingalternately several times the steps of: a first step of forming a layerof nitride or carbonitride (C/N atomic ratio being from 0.3/0.7 to 0/1),1 to 80 nm in thickness, by ion-plating or sputtering with a targetrepresented by the formula (1c) below,(Cr_((1-a))Al_(a))  (1c), or the formula (1d) below,(Cr_((1-a-b-c))Al_(a)Si_(b)B_(c))  (1d); and a second step of forming alayer of nitride or carbonitride (C/N atomic ratio being from 0.5/0.5 to0/1), 1 to 80 nm in thickness, by ion-plating or sputtering with atarget represented by the formula (2c) below,(Zr_((1-k))Hf_(k))  (2c), or the formula (2d) below,(Zr_((1-k-m-n))Hf_(k)Si_(m)B_(n))  (2d), where 0.2≦a≦0.8, 0<(b+c)≦0.2,0≦k≦1 (for the formula 2c), 0≦k≦1-m-n (for the formula 2d), 0≦(m+n)≦0.2,either of b and c possibly is 0, and either of m and n possibly is
 0. 6.The hard coating film of laminate type according to claim 1, wherein atleast one of the more than one layer of a first kind and the more thanone layer of a second kind possesses the cubic crystal structure.
 7. Thehard coating film of laminate type according to claim 2, wherein atleast one of the more than one layer of a first kind and the more thanone layer of a second kind possesses the cubic crystal structure.
 8. Thehard coating film of laminate type according to claim 3, wherein atleast one of the more than one layer of a first kind and the more thanone layer of a second kind possesses the cubic crystal structure.
 9. Thehard coating film of laminate type according to claim 4, wherein atleast one of the more than one layer of a first kind and the more thanone layer of a second kind possesses the cubic crystal structure. 10-18.(canceled)
 19. The hard coating film according to claim 1, which has athickness no smaller than 1000 nm.
 20. The hard coating film accordingto claim 2, which has a thickness no smaller than 1000 nm.
 21. The hardcoating film according to claim 3, which has a thickness no smaller than1000 nm.
 22. The hard coating film according to claim 4, which has athickness no smaller than 1000 nm.
 23. The hard coating film accordingto claim 5, which has a thickness no smaller than 1000 nm.
 24. The hardcoating film according to claim 6, which has a thickness no smaller than1000 nm.
 25. The hard coating film according to claim 7, which has athickness no smaller than 1000 nm.
 26. The hard coating film accordingto claim 8, which has a thickness no smaller than 1000 nm.
 27. The hardcoating film according to claim 9, which has a thickness no smaller than1000 nm. 28-36. (canceled)